In video coding, quantized transform coefficients, as well as motion vectors describing relative motion between a block to be encoded and a reference block, may be referred to as “syntax elements.” Syntax elements, along with other control information, may form a coded representation of the video sequence. In some examples, prior to transmission from an encoder to a decoder, syntax elements may be entropy coded, thereby further reducing a number of bits needed for their representation. Entropy coding may be described as a lossless operation aimed at minimizing a number of bits required to represent transmitted or stored symbols (e.g., syntax elements) by utilizing properties of their distribution (e.g., some symbols occur more frequently than others).
One method of entropy coding employed by video coders is Variable Length Coding (VLC). According to VLC, a VLC codeword (a sequence of bits (0's and 1's)), may be assigned to each symbol (e.g., syntax element). VLC code words may be constructed such that a length of the codeword corresponds to how frequently the symbol represented by the codeword occurs. For example, more frequently occurring symbols may be represented by shorter VLC code words. In addition, VLC code words may be constructed such that the code words are uniquely decodable. For example if a decoder receives a valid sequence of bits of a finite length, there may be only one possible sequence of input symbols that, when encoded, would produce the received sequence of bits.